Facile access to new pyrido[2,3-d]pyrimidine derivatives.

In this report, a facile, operationally, simple and highly efficient one-pot coupling of 2,6-diaminopyrimidin-4(3H)-one and ethyl-2,4-dioxo-4-phenylbutanoate derivatives is reported. This method afforded a novel series of ethyl-2-amino-3,4-dihydro-4-oxo-5-phenyl pyrido[2,3-d] pyrimidine-7-carboxylate heterocycle derivatives in high yields under refluxing AcOH.